1. Field of the Invention
The present invention relates to a fluid filter, more specifically, to a fluid filter which can ensure a filtration area while suppressing deformation of a filter material, thereby improving the filtration efficiency.
2. Description of the Related Art
Conventionally, as a fluid filter used for an automatic transmission of a vehicle and the like, for example, as shown in FIGS. 12A and 12B, a fluid filter including an upper case member 102 having a flow outlet 102a; a lower case member 103 having a flow inlet 103a; and a filter element 106 having a folded filter material 104 and a holding frame 105 which holds the circumferential part of the filter material 104 and is sandwiched between the cases 102 and 103 is generally known. Such fluid filters involved the problem, for example, that the filter material 104 is deformed by the pressure when a fluid passes therethrough so that the folds are in close contact, as shown in FIGS. 13A and 13B, resulting in a decrease in filtration area.
Therefore, in order to prevent the close contact between the folds, it is known to use a comb-like reinforcing member, a rib or the like to suppress deformation of the filter material (see, for example, Related Art 1).    [Related Art 1] JP-A-2004-353783
However, the comb-like reinforcing member, rib or the like for suppressing deformation of the filter material involved the problem that it is provided in close contact with or in abutment with the filter material, thereby causing a decrease in filtration area.